Switch



Patenied oct. 2o, 1942 SWITCH Ernst Walter Rickmeyer, Elmhurst,Ill.,assignor to Jefferson Electric Company, Bellwood, Ill.,

a corporation of Illinois Application January 2, 1942, Serial No.425,393

(Cl. ZIN-152) 8 Claims.

This invention relates to switches, and more particularly to switches inwhich a fluid contacting element is utilized to make and break anelectrical circuit.

In switches utilizing a fluid contacting element, such as mercury, asmall operating angle for eiecting the Control of the ilow of mercuryb-etween the circuit making and breaking positions is often desirable.Also, due to the inherent surface tension of mercury or other similarfluid contacting elements and the desirability of effecting the makingand breaking of the electrical circuit between mercury surfaces, it isimportant that the mercury in the switch is separated while remaining incontact with a suflicient surface of mercury contacting electrodes ofthe switch to minimize the contact resistance of the switch.

An object of this invention is to provide a switch in which a fluidcontacting element is utilized to make and break an electrical circuit,and

in which a very small angular movement of the switch is required toeffect the making and breaking of the circuit.

Another object of this invention is to provide a switch in which a fluidcontacting element having high surface tension characteristics is uti-llized to make and break an electrical cir-cuit, and in which contact ismade and broken between quantities of the contacting fluid while keeping,l suiiicient quantities of the iiuid in contact with the switchelectrodes to keep the contact resistance of the switch low.

Another object of this invention is to provide a mercury switch having ametal enclosing shell which serves as one electrode of the switch andincluding fixed and movable bodies of mercury between which the circuitis made and broken, the switch design being such that the Xed body ofVmercury has a relatively large area of contact with one electrode andis coni-ined in such a way that retention of the xed quantity in placeis insured.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein a preferred embodiment of the present invention isclearly shown.

In the drawing:

Figure 1 is a side sectional View of a switch embodying a preferred formof the present invention;

Figures 2 and 3 are sectional views of the switch shown in Figure 1 withthe sections taken respectively on the lines 2-2 and 3 3 of Figure 1 andviewed in the direction indicated by the arrows;

Figure 4 is a perspective view of a part of the switch shown in Figure1;

Figure 5 is a side sectional View of a, switch embodying a modified formof the present invention;

Figures 6 and 7 are sectional views of the switch shown in Figure 5,with the sections taken respectively on lines 6-6 and 'I-l of Figure 5and viewed in the direction indicated by the arrows; and

Figure 8 is a perspective View of a part of the switch shown in Figure5.

Having particular reference to Figures l to 4 inclusive, the switchdisclosed has a metal outer shell I6 which provides a housing for theswitch and serves as one of the electrodes. This outer shell or housingI Il is preferably made of substantially or commercially pure soft ironwhich does not contain impurities which would effect amalgamation oroxidize or corrode. Also, at least the inner surface is preferablythoroughly cleaned so that all oxide iilm 4and impurities are removed atthe time the switch is assembled. The housing or shell II] has a closedend I2 and an open end I3, and is preferably lined with insulatingmaterial, such as ceramic material at the closed end I2 and to aposition near the open end I3. The insulating or ceramic lining, forconvenience in manufacture, preferably comprises adjoining parts I4 andI5. The lining part I5 is preferably a hollow sleeve in which an inneropening I6 which extends therethrough is tapered to be larger near theopen end of the shell than near the closed end of the shell. The liningpiece I4 has a recess or depression I'I which is in alignment with theend of the opening I6 of the lining part I57 and has a channel I8 whichextends from the recess Il to the inner wall of the shell Ill. The endof the lining part I5 is closely abutted against the inner end of thelining part I4 and provides a sharp angular edge at I9 adjacent thechannel I8.

An inner electrode 20 has a disc-like end portion 22 which abuts againstand is located by a shoulder 23 on the lining part I5 near the open endof the shell I0 and is separated from the shell by a liange 24 on theend of the lining part I5. The electrode 20 has an integral tongueportion 25 which conforms to and extends inwardly along the surface ofthe inner opening It in the lining part I5 to a position near the edgeI9 at the inner end of the opening I6. A terminal member 26 has a stem28 which projects from the open end of the shell lil and has its outersurface threaded at 29 for making electrical connections thereto. Thestem preferably has an opening 30 therein in alignment with an opening32 in the end portion 22 of the electrode 2l) which communicates withthe switch chamber provided by the opening I6. An insulating washer 33lits snugly into the open end of the shell I0 and snugly around the stem28, and abuts against the outer surface of the disclike portion 21 ofthe terminal member 26. This insulated washer is preferably made ofrelatively soft rubber which expands upon the application of pressurethereto to provide a gas-tight seal. A second insulating washer 34 ofrelatively rigid insulating material covers the outer end of theinsulating washer 33 and is pressed in position by a metallic washer 35against which the end surface of the open end of the shell I is swedgedor rolled as at 36 to hold the switch parts in assembled relation andapply sealing pressure to the washer 33. 'Ihe washer 35 has a largeopening 36 through which the stem 23 extends in spaced relation thereto.

A quantity of mercury is enclosed in the switch chamber, a portion 371of which is normally trapped in the channel I8 and a portion 38 of whichis movable along and in contact with the tongue portion 25 of the innerelectrode 2B upon tilting of the switch to make and break a circuitbetween the inner electrode 29 and the outer electrode or shell i0through the portion 31 of the mercury. The longitudinal dimension orwidth of the channel i8, as viewed in Figure 1, is such that the trappedportion of the mercury 31 extends substantially meniscus height abovethe edge I9. The depth of the channel i3 is such, and is so related tothe longitudinal dimension thereof that the trapped quantity of mercuryis stable and will remain in the channel during movements of the switchthroug-h any normal operating angles. The side walls of the channel I8,as viewed in Figure 3, are preferably substantially radial with respectto the shell iii or diverge outwardly toward the shell to provide alarge surface area of contact between the trapped quantity of mercury 31and the shell il Since the trapped mercury 31 is retained and stable,and since the edge I9 is sharp, the making and breaking of Vthe circuitoccurs between the two bodies of mercury, rather than between a body ofmercury and one of the electrodes when the switch is moved throughnormal operating angles.

After the mechanical assembly of the switch, it is preferable that theair is pumped from the interior of the switch through the openings 3i!and 32, and that the switch is then lled with non-oxidizing gas, such ashydrogen, under a pressure sufficient to minimize arcing. After the gaslling, a plug 39 is pressed linto the opening 3i) -to complete thesealing of the switch chamber. This prevents oxidation or corrosion ofthe mercury and limits the arcing between the bodies of mercury when thecircuit is opened and closed by the switch.

Having particular reference to Figures to 8 inclusive, parts bearingreference numerals similar to those used in the description of Figures 1to 4 inclusive are similar and Vperform substantially similar functions.The switch shown in Figures 1 to 4 inclusive is wha-t is called ya oneposition switch. With this type of switch, the electrode and the channelI8 should be on the bottom, when the switch is in an operative position,so that the movable portion of the mercury 38 moves along the surface ofthe inner electrode and into and away from engagement with the trappedportion of the mercury 31. The switch shown in Figures 5 to 8 inclusiveis adapted to operate in any position about its longitudinal axis inwhich it may be placed for operation.

In the switch shown in Figures 5 to 8 inclusive, the metallicshell l0has therein a cylindrical insulating sleeve 39 made of a material suchas a ceramic. An opening 4E) extends longitudinally through the sleeveand has a cylindrical metallic electrode 42 mounted therein whichextends from the end of the insulating sleeve 39 which is near the openend I3l of the shell to a position near but spaced from the other end of4the insulating sleeve 39. A second insulating lining part 43 which isalso preferably made of ceramic material ts into the closed end I2 ofthe shell I@ and preferably has a plurality of integral feet 44 thereonwhich are preferably small in comparison with the surface of theinsulating part and serve to space the second insulating lining part 43from the end of the insulating sleeve 39 to provide a circumferentialchannel 45 within the shell IJ, in which channel a quantity of mercury31 is trapped. This channel 45, like the channel I8 in Figure 1, is soproportioned that the trapped mercury 31 extends substantially meniscusheight above an edge 46 at the end of the insulating sleeve 39 and isstable. The edge 46 is preferably angular and sharp, so that with thestable body of mercury 31 trapped in the channel 45 in contact with theshell I3, the cir- -cuit through the switch is made and broken betweenthe trapped and movable quantities of mercury at or near the edge 45.Since the feet 44 are small and are widely spaced apart, the rotation ofthe switch about its longitudinal axis does not prevent the trappedmercury 31 from remaining in contact with the shell l0. Also, since theelectrode 4.2 is cylindrical, the movable quantity of mercury 38 remainsin contact with that electrode as the switch is rotated about itslongitudinal axis.

The electrode 42 preferably has a flanged -edge 41 which engages ashoulder 43 on the insulatin-g sleeve 39. Also, the hanged edge 41 andthe disc-like portion 21 are spaced and insulated from the metallicshell I3 by an extending flange 49 on the insulating sleeve 33. Thesealing and preferable gas .filling of the switch are substantially thesame as described in connection with the switch shown in Figures 1 to linclusive.

, I'he structure of both switches is such that they lend themselves wellto operation with only small angular movements which eiect theoperation.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other for-msmight be adopted, all coming within the scope of the claims whichfollow.

I claim:

1. A mercury switch comprising, in combination, a cylindrical 'metalshell providing one electrode and having a closed end and an open end, alining of insulating material fitting into said shell and having an openend adjacent the open end of the shell, said lining having an openingbetween the ends thereof and near the closed end of the shell, saidopening beiner dened by substantially parallel end walls and side wallswhich are substantially radial with respect to the cylindrical shell, asecond electrode insulated from the metal shell by said lining andextending inwardly along the lining from near the open end of the shell,means closing the open end of the shell exterior of the lining andelectrode means for making an electrical connection to the secondelectrode, and a lquantity of mercury within the closed shell, saidquantity of mercury being sufcient to provide a stable body in saidopening in contact with the shell, and a movable body adaptedto bridgethe gap between the Istable body and the second electrode and cover aportion of the surface of the second electrode While bridging said gapand when said shell is disposed at a predetermined angle.

2. A mercury switch comprising, in combination, a cylindrical metalshell providing one electrode and having a closed end and an open end, alining of ceramic material having an cuter surface contiguous to theinner surface of the shell and having an open end adjacent the open endof the shell, said lining having a pair of end walls spaced apart toprovide an opening near the closed end of the shell and having anaxially extending adjoining opening, a second electrode tting into andclosing the open end of the lining and having a portion extending towardthe first mentioned opening, means closing the open end of the shellexterior to the second electrode and lining, means for making anelectrical connection to the second electrode, a quantity of mercurywithin the shell and lining, said pair of end walls being spaced by anamount such that a stable quantity of mercury is trapped therebetween incontact with the shell, and said quantity of mercury being such as toprovide a movable body adapted to bridge the space between the secondelectrode and said stable quantity of mercury when the shell is disposedat a predetermined angle.

3. A mercury switch comprising, in combination, a cylindrical metalshell providing one electrode and having a closed end and an open end,an insulating lining within said shell including a pair of cooperatingparts, one of said parts being hollow and having an inner surfacetapering outwardly toward the open end of the shell, means integral withone of said parts spacing the pair of parts to provide an o-peningtherebetween, a second electrode extending along the inner surface ofsaid hollow part and having an end spaced from said opening, meansclosing the open end of the shell exterior to the second electrode andlining, means for making an electrical connection to the secondelectrode, and a quantity of mercury within the closed shell, thespacing of said parts and the quantity of mercury being such that a bodyof mercury is retained in said opening between the parts and in contactwith the shell and a second body of mercury is movable into and out ofbridging engagement between the retained body of mercury and the secondelectrode.

4. A mercury switch comprising, in combination, a hollow metal shellproviding one electrode and having a closed end and an open end, aninsulating lining within the shell including a pair of cooperatingparts, one of said parts being tubular, means intermediate the parts andspacing the parts to provide an opening therebetween, a second electrodeextending along the inner surface of the tubular part and having an endspaced from the opening, insulating means closing the open end of theshell exterior to the second electrode and lining, means extendingthrough the insulating means for making an electrical connection to thesecond electrode, and a quantity of mercury within the closed shell, thespacing of said parts and the quantity of mercury being such that a bodyof mercury is retained in said opening between the parts and in contactwith the shell and a second body of mercury is movable into and out ofbridging engagement between the retained body of mercury and the secondelectrode.

5. A mercury switch comprising, in combination, a hollow metal shellproviding one electrode and having a closed end and an open end, aninsulating lining within the shell including a pair of cooperatingparts, one of said parts being tubular, means comprising a plurality ofspaced iingers intermediate the parts and spacing the parts to providean opening therebetween, a second electrode comprising a tubularconductive element extending along the inner surface of the tubular partand having an end spaced fromv the opening, insulating means closing theopen end of the shell exterior to the second electrode and lining, meansextending through the insulating means for making an electricalconnection to the second electrode, and a quantity of mercury within theclosed shell, the spacing of said parts and the quantity of mercurybeing such that a body of mercury is retained in said opening betweenthe parts and in contact with the shell and a second body of mercury ismovable into and out of bridging engagement between the retained body ofmercury and the second electrode.

6. In a mercury switch, the combination comprising a metallic shell, aquantity of mercury, a lining of insulating material iitting into theshell and having two cooperating parts, one of said parts being tubular,said parts having an opening therebetween, and said tubular part havinga relatively sharp edge adjacent said opening, the dimensions of saidopening being such that mercury trapped therein contacts the shell andextends substantially meniscus height above said edge.

'7. A mercury switch adapted to make and break an electrical circuitupon movement to predetermined angular positions and comprising, incombination, a metallic shell providing one electrode and having aclosed end and an open end, an insulating lining within the shell havingan opening therethrough, a second electrode insulated from the shell andextending toward said opening from the open end of the shell, meansclosing the open end of the shell, means for making an electricalconnection to the second electrode, a quantity of mercury within theclosed shell, a portion of said mercury being disposed in said openingin contact with the shell and the remainder being adapted to move withinthe shell to make and break an electrical circuit between theelectrodes, said opening, said second electrode and the quantity ofmercury being such that the areas of contact of the mercury with each ofthe electrodes is larger than the cross sectional area of the mercurywhen said mercury makes the circuit between the electrodes.

8. A mercury switch comprising, in combination, a metal shell open atone end and closed at the other end, said shell serving as one electrodeof the switch, a quantity of mercury Within the shell, means retaininga, substantially iixed quantity of mercury in contact with the shell ina xed position, a second electrode insulated from the shell andextending into the shell toward the retained mercury, a movable body ofmercury in contact with the second electrode and adapted to electricallyconnect the second electrode and retained mercury, means closing theopen end of the shell, and means for making an electrical connection tothe second electrode.

ERNST WALTER RICKMEYER.

